Thursday, September 28, 2023

Birds and Weird Dinosaurs

 There is still so much to discover. From Nature:

One hundred and fifty million years ago, a young, bantam-sized, bird-like dinosaur became mired in a swamp in what is now southeastern China, and succumbed. Its fossilized remains, unearthed in 2022 and named Fujianvenator prodigiosus, show it to be one of the earliest bird-like dinosaurs to date from the Jurassic period. The researchers describe their discovery in a paper published today in Nature1.

“This is really a weird animal within the group of birds,” says Mark Loewen, a palaeontologist at the University of Utah in Salt Lake City, who was not involved in the discovery.

The creature had oddly lanky legs and might have lacked the ability to fly. It also doesn’t seem to conform to the accepted bird-evolution story.

Although dinosaurs were largely extinct by 66 million years ago, therapods, the three-clawed, hollow-boned group that included Velociraptor and Tyrannosaurus rex, had started to evolve into today’s birds. Many palaeontologists consider the first bird to be a 150-million-year-old feathered dinosaur called Archaeopteryx, fossils of which were found in Germany. But this study adds to mounting evidence that by the time of Archaeopteryx, dinosaurs had already diversified into different kinds of birds, Loewen says.

Hailu You, a palaeontologist at the Chinese Academy of Sciences in Beijing and one of the co-authors of the paper, says that in the Jurassic, bird-like dinosaurs might have been occupying different ecological niches. “Early bird evolution is complicated,” he says.

Fujianvenator’s fossil lacks a head and a complete tail, but its body and limbs show a medley of traits similar to those of other bird-like dinosaurs, such as the relative lengths of the fingers, and details of the pelvis and vertebrae.

But it didn’t have many modifications that would contribute to flight. For example, it had a shortened shoulder blade and fingers more specialized for grabbing. Strangest of all are the bird’s hyper-elongated hind legs, in which the lower leg bone — the tibia — is twice as long as the thigh bone. Such long legs indicate a highly skilled runner, perhaps similar to a roadrunner (Geococcyx spp.), says Bhart-Anjan Bhullar, a palaeontologist at Yale University in New Haven, Connecticut. (Read more.)

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